Proteomic responses to progressive dehydration stress in leaves of chickpea seedlings

Zinc finger knuckle genes are associated with tolerance to drought and dehydration in chickpea (Cicer arietinum L.)

Chickpea (Cicer arietinum L.) is a very important food legume and needs improved drought tolerance for higher seed production in dry environments. The aim of this study was to determine diversity and genetic polymorphism in zinc finger knuckle genes with CCHC domains and their functional analysis for practical improvement of chickpea breeding. Two CaZF-CCHC genes, Ca04468 and Ca07571, were identified as potentially important candidates associated with plant responses to drought and dehydration. To study these genes, various methods were used including Sanger sequencing, DArT (Diversity array technology) and molecular markers for plant genotyping, gene expression analysis using RT-qPCR, and associations with seed-related traits in chickpea plants grown in field trials. These genes were studied for genetic polymorphism among a set of chickpea accessions, and one SNP was selected for further study from four identified SNPs between the promoter regions of each of the two genes. Molecular markers were developed for the SNP and verified using the ASQ and CAPS methods. Genotyping of parents and selected breeding lines from two hybrid populations, and SNP positions on chromosomes with haplotype identification, were confirmed using DArT microarray analysis. Differential expression profiles were identified in the parents and the hybrid populations under gradual drought and rapid dehydration. The SNP-based genotypes were differentially associated with seed weight per plant but not with 100 seed weight. The two developed and verified SNP molecular markers for both genes, Ca04468 and Ca07571, respectively, could be used for marker-assisted selection in novel chickpea cultivars with improved tolerance to drought and dehydration.

Uncovering proteome variations and concomitant quality changes of differently drying-treated rape (Brassica napus) bee pollen by label-free quantitative proteomics

High moisture content of fresh bee pollen makes it difficult to preserve and thus makes drying a necessary process during the bee pollen production. Drying treatment will affect its quality and the effects of sun drying, hot-air drying and freeze drying on the proteome of rape (Brassica napus) bee pollen have been evaluated using label-free quantitative proteomics by liquid chromatography-tandem mass spectrometer (LC-MS/MS). A total of 8377 proteins are identified, among which the most abundant differential proteins were found in freeze drying-treated samples. Also freeze-drying treatment maximizes the content of antioxidant, antibacterial and anemic bioactive pollen protein. Besides, rape bee pollen is found to adjust its metabolism to protect itself during the drying process. These results can be favorable to evaluate the effects of drying treatment on the nutrition and function of processed rape bee pollen and insight into how rape bee pollen proteins respond to dehydration.

Comprehensive Proteomic Analysis of Common Bean (Phaseolus vulgaris L.) Seeds Reveal Shared and Unique Proteins Involved in Terminal Drought Stress Response in Tolerant and Sensitive Genotypes

This study identified proteomic changes in the seeds of two tolerant (SB-DT3 and SB-DT2) and two sensitive (Merlot and Stampede) common bean genotypes in response to terminal drought stress. Differentially expressed proteins (DEPs) were abundant in the susceptible genotype compared to the tolerant line. DEPs associated with starch biosynthesis, protein-chromophore linkage, and photosynthesis were identified in both genotypes, while a few DEPs and enriched biological pathways exhibited genotype-specific differences. The tolerant genotypes uniquely showed DEPs related to sugar metabolism and plant signaling, while the sensitive genotypes displayed more DEPs involved in plant-pathogen interaction, proteasome function, and carbohydrate metabolism. DEPs linked with chaperone and signal transduction were significantly altered between both genotypes. In summary, our proteomic analysis revealed both conserved and genotype-specific DEPs that could be used as targets in selective breeding and developing drought-tolerant common bean genotypes.

Prioritization of Physio-Biochemical Selection Indices and Yield-Attributing Traits toward the Acquisition of Drought Tolerance in Chickpea (Cicer arietinum L.)

Chickpea is widely grown in rainfed areas of developing countries because of its nutritional abundance and adaptability. To overcome the environmental effect of drought on yield, a characteristic-linked selection strategy is proved as well-thought-out and advantageous for the development of drought-tolerant cultivars. To precisely understand the contribution of various physio-biochemical and yield-attributing traits toward drought tolerance in chickpea (Cicer arietinum L.), forty chickpea genotypes were evaluated in the years 2020-2021 and 2021-2022 under normal irrigated as well as drought-stressed conditions. Among the studied genotypes, genotype ICC4958 retained the highest chl content (0.55 mg g-1 FW), minimal electrolyte leakage, and superoxide dismutase (1.48 U/mg FW) and peroxidase (2.21 µmol/min/g FW) activities while cultivar JG11 maintained the maximum relative water content and proline accumulation. The principal-component-based biplots prioritized the physio-biochemical and yield-accrediting characteristics based on their association significance and contribution to terminal drought tolerance. Under drought stress, grain yield per plant was depicted to have a strongly positive association with canopy temperature depression, catalase, superoxide dismutase, and peroxidase activities as well as total soluble sugar, proline, and chlorophyll content, along with the numbers of pods and biological yield per plant. These identified physio-biochemical and yield-attributing traits can be further deployed to select drought-tolerant chickpea genotypes for the breeding of climate-smart chickpea genotypes.

Unravelling the molecular mechanism underlying drought stress response in chickpea via integrated multi-omics analysis

Drought stress affects growth and productivity significantly in chickpea. An integrated multi-omics analysis can provide a better molecular-level understanding of drought stress tolerance. In the present study, comparative transcriptome, proteome and metabolome analyses of two chickpea genotypes with contrasting responses to drought stress, ICC 4958 (drought-tolerant, DT) and ICC 1882 (drought-sensitive, DS), was performed to gain insights into the molecular mechanisms underlying drought stress response/tolerance. Pathway enrichment analysis of differentially abundant transcripts and proteins suggested the involvement of glycolysis/gluconeogenesis, galactose metabolism, and starch and sucrose metabolism in the DT genotype. An integrated multi-omics analysis of transcriptome, proteome and metabolome data revealed co-expressed genes, proteins and metabolites involved in phosphatidylinositol signaling, glutathione metabolism and glycolysis/gluconeogenesis pathways, specifically in the DT genotype under drought. These stress-responsive pathways were coordinately regulated by the differentially abundant transcripts, proteins and metabolites to circumvent the drought stress response/tolerance in the DT genotype. The QTL-hotspot associated genes, proteins and transcription factors may further contribute to improved drought tolerance in the DT genotype. Altogether, the multi-omics approach provided an in-depth understanding of stress-responsive pathways and candidate genes involved in drought tolerance in chickpea.

Genome-wide association study in two-row spring barley landraces identifies QTL associated with plantlets root system architecture traits in well-watered and osmotic stress conditions

Water availability is undoubtedly one of the most important environmental factors affecting crop production. Drought causes a gradual deprivation of water in the soil from top to deep layers and can occur at diverse stages of plant development. Roots are the first organs that perceive water deficit in soil and their adaptive development contributes to drought adaptation. Domestication has contributed to a bottleneck in genetic diversity. Wild species or landraces represent a pool of genetic diversity that has not been exploited yet in breeding program. In this study, we used a collection of 230 two-row spring barley landraces to detect phenotypic variation in root system plasticity in response to drought and to identify new quantitative trait loci (QTL) involved in root system architecture under diverse growth conditions. For this purpose, young seedlings grown for 21 days in pouches under control and osmotic-stress conditions were phenotyped and genotyped using the barley 50k iSelect SNP array, and genome-wide association studies (GWAS) were conducted using three different GWAS methods (MLM GAPIT, FarmCPU, and BLINK) to detect genotype/phenotype associations. In total, 276 significant marker-trait associations (MTAs; p-value (FDR)< 0.05) were identified for root (14 and 12 traits under osmotic-stress and control conditions, respectively) and for three shoot traits under both conditions. In total, 52 QTL (multi-trait or identified by at least two different GWAS approaches) were investigated to identify genes representing promising candidates with a role in root development and adaptation to drought stress.

PS II Subunit P in Lilium pumilum (LpPsbP) Confers Saline-Alkali Resistance to the Plant by Scavenging ROS

(1) Background: The growth of plants is impacted by salinity and alkali, Lilium pumilum (L. pumilum) is an ornamental plant with strong resistance to salinity and alkali, while the LpPsbP gene is helpful to fully understand the Saline-Alkali tolerance of L. pumilum. (2) Methods: Gene cloning, bioinformatics analysis, expression of fusion protein, determination of physiological indices of plant after Saline-Alkali stress, yeast two-hybrid screening, luciferase complementation assay, chromosome walking to obtain the promoter sequence, and then analyzed by PlantCARE. (3) Results: The LpPsbP gene was cloned and the fusion protein was purified. The transgenic plants had higher Saline-Alkali resistance than the wild type. A total of eighteen proteins interacting with LpPsbP were screened, and nine sites in the promoter sequence were analyzed. (4) Conclusion: Under Saline-Alkali or oxidative stress, L. pumilum will promote the expression of LpPsbP, which will then directly scavenge reactive oxygen species (ROS) in order to protect its photosystem II, reduce its damage, and thus improve the Saline-Alkali resistance of the plant. Moreover, according to some of the literature and the following experiments, two additional speculations are developed on the mechanisms of how two newly found objects, namely jasmonic acid (JA) and FoxO protein, could be involved in ROS scavenging processes were made.

Genome-wide association analysis for drought tolerance and associated traits in faba bean (Vicia faba L.)

Faba bean (Vicia faba L.) is an important high protein legume adapted to diverse climatic conditions with multiple benefits for the overall sustainability of the cropping systems. Plant-based protein demand is being expanded and faba bean is a good candidate to cover this need. However, the crop is very sensitive to abiotic stresses, especially drought, which severely affects faba bean yield and development worldwide. Therefore, identifying genes associated with drought stress tolerance is a major challenge in faba bean breeding. Although the faba bean response to drought stress has been widely studied, the molecular approaches to improve drought tolerance in this crop are still limited. Here we built on recent genomic advances such as the development of the first high-density SNP genotyping array, to conduct a genome-wide association study (GWAS) using thousands of genetic polymorphisms throughout the entire faba bean genome. A worldwide collection of 100 faba bean accessions was grown under control and drought conditions and 10 morphological, phenological and physiological traits were evaluated to identify single nucleotide polymorphism (SNP) markers associated with drought tolerance. We identified 29 SNP markers significantly correlated with these traits under drought stress conditions. The flanking sequences were blasted to the Medicago truncatula reference genomes in order to annotate potential candidate genes underlying the causal variants. Three of the SNPs for chlorophyll content after the stress, correspond to uncharacterized proteins indicating the presence of novel genes associated with drought tolerance in faba bean. The significance of stress-inducible signal transducers provides valuable information on the possible mechanisms underlying the faba bean response to drought stress, thus providing a foundation for future marker-assisted breeding in the crop.

Susceptibility of Rice Crop to Salt Threat: Proteomic, Metabolomic, and Physiological Inspections

Rice is a staple food crop worldwide; however, salinity stress is estimated to reduce its global production by 50%. Knowledge about initial molecular signaling and proteins associated with sensing salinity among crop plants is limited. We characterized early salt effects on the proteome and metabolome of rice tissues. Omics results were validated by western blotting and multiple reaction monitoring assays and integrated with physiological changes. We identified 8160 proteins and 2045 metabolites in rice tissues. Numerous signaling pathways were induced rapidly or partially by salinity. Combined data showed the most susceptible proteins or metabolites in each pathway that likely affected the sensitivity of rice to salinity, such as PLA1, BON3 (involved in sensing stress), SnRK2, pro-resilin, GDT1, G-proteins, calmodulin activators (Ca²⁺ and abscisic acid signaling), MAPK3/5, MAPKK1/3 (MAPK pathway), SOS1, ABC F/D, PIP2-7, and K⁺ transporter-23 (transporters), OPR1, JAR1, COL1, ABA2, and MAPKK3 (phytohormones). Additionally, our results expanded the stress-sensing function of receptor-like kinases, phosphatidylinositols, and Na⁺ sensing proteins (IPUT1). Combined analyses revealed the most sensitive components of signaling pathways causing salt-susceptibility in rice and suggested potential targets for crop improvement.

Molecular Breeding and Drought Tolerance in Chickpea

Cicer arietinum L. is the third greatest widely planted imperative pulse crop worldwide, and it belongs to the Leguminosae family. Drought is the utmost common abiotic factor on plants, distressing their water status and limiting their growth and development. Chickpea genotypes have the natural ability to fight drought stress using certain strategies viz., escape, avoidance and tolerance. Assorted breeding methods, including hybridization, mutation, and marker-aided breeding, genome sequencing along with omics approaches, could be used to improve the chickpea germplasm lines(s) against drought stress. Root features, for instance depth and root biomass, have been recognized as the greatest beneficial morphological factors for managing terminal drought tolerance in the chickpea. Marker-aided selection, for example, is a genomics-assisted breeding (GAB) strategy that can considerably increase crop breeding accuracy and competence. These breeding technologies, notably marker-assisted breeding, omics, and plant physiology knowledge, underlined the importance of chickpea breeding and can be used in future crop improvement programmes to generate drought-tolerant cultivars(s).

Recent advancement in OMICS approaches to enhance abiotic stress tolerance in legumes

The world is facing rapid climate change and a fast-growing global population. It is believed that the world population will be 9.7 billion in 2050. However, recent agriculture production is not enough to feed the current population of 7.9 billion people, which is causing a huge hunger problem. Therefore, feeding the 9.7 billion population in 2050 will be a huge target. Climate change is becoming a huge threat to global agricultural production, and it is expected to become the worst threat to it in the upcoming years. Keeping this in view, it is very important to breed climate-resilient plants. Legumes are considered an important pillar of the agriculture production system and a great source of high-quality protein, minerals, and vitamins. During the last two decades, advancements in OMICs technology revolutionized plant breeding and emerged as a crop-saving tool in wake of the climate change. Various OMICs approaches like Next-Generation sequencing (NGS), Transcriptomics, Proteomics, and Metabolomics have been used in legumes under abiotic stresses. The scientific community successfully utilized these platforms and investigated the Quantitative Trait Loci (QTL), linked markers through genome-wide association studies, and developed KASP markers that can be helpful for the marker-assisted breeding of legumes. Gene-editing techniques have been successfully proven for soybean, cowpea, chickpea, and model legumes such as Medicago truncatula and Lotus japonicus. A number of efforts have been made to perform gene editing in legumes. Moreover, the scientific community did a great job of identifying various genes involved in the metabolic pathways and utilizing the resulted information in the development of climate-resilient legume cultivars at a rapid pace. Keeping in view, this review highlights the contribution of OMICs approaches to abiotic stresses in legumes. We envisage that the presented information will be helpful for the scientific community to develop climate-resilient legume cultivars.

Regulation and physiological function of proteins for heat tolerance in cowpea (Vigna unguiculata) genotypes under controlled and field conditions

The expression of heat shock proteins is considered a central adaptive mechanism to heat stress. This study investigated the expression of heat shock proteins (HSPs) and other stress-protective proteins against heat stress in cowpea genotypes under field (IT-96D-610 and IT-16) and controlled (IT-96D-610) conditions. Heat stress response analysis of proteins at 72 h in the controlled environment showed 270 differentially regulated proteins identified using label-free quantitative proteomics in IT-96D-610 plants. These plants expressed HSPs and chaperones [BAG family molecular chaperone 6 (BAG6), Multiprotein bridging factor1c (MBF1C) and cold shock domain protein 1 (CSDP1) in the controlled environment]. However, IT-96D-610 plants expressed a wider variety of small HSPs and more HSPs in the field. IT-96D-610 plants also responded to heat stress by exclusively expressing chaperones [DnaJ chaperones, universal stress protein and heat shock binding protein (HSBP)] and non-HSP proteins (Deg1, EGY3, ROS protective proteins, temperature-induced lipocalin and succinic dehydrogenase). Photosynthesis recovery and induction of proteins related to photosynthesis were better in IT-96D-610 because of the concurrent induction of heat stress response proteins for chaperone functions, protein degradation for repair and ROS scavenging proteins and PSII operating efficiency (Fq'/Fm') than IT-16. This study contributes to identification of thermotolerance mechanisms in cowpea that can be useful in knowledge-based crop improvement.

De novo transcriptome analysis identifies key genes involved in dehydration stress response in kodo millet (Paspalum scrobiculatum L.)

Kodo millet (Paspalum scrobiculatum L.) is a small millet species known for its excellent nutritional and climate-resilient traits. To understand the genes and pathways underlying dehydration stress tolerance of kodo millet, the transcriptome of cultivar 'CO3' subjected to dehydration stress (0 h, 3 h, and 6 h) was sequenced. The study generated 239.1 million clean reads that identified 9201, 9814, and 2346 differentially expressed genes (DEGs) in 0 h vs. 3 h, 0 h vs. 6 h, and 3 h vs. 6 h libraries, respectively. The DEGs were found to be associated with vital molecular pathways, including hormone metabolism and signaling, antioxidant scavenging, photosynthesis, and cellular metabolism, and were validated using qRT-PCR. Also, a higher abundance of uncharacterized genes expressed during stress warrants further studies to characterize this class of genes to understand their role in dehydration stress response. Altogether, the study provides insights into the transcriptomic response of kodo millet during dehydration stress.

Identifying Novel Genes and Proteins Involved in Salt Stress Perception and Signaling of Rice Seedlings

Rice is one of the most important crops worldwide. Crop production is constrained markedly, however, by abiotic stresses such as salinity. To elucidate early stress response signaling networks involved in rice, we report in this study an original quantitative proteomic analysis of the rice seedlings subjected to short-term salt stress. We detected 570 differentially regulated proteins (DRPs) in the root sample. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis demonstrated that DRPs of the root were mainly involved in membrane trafficking, kinase activity, and ion toxicity responses. Interactome analysis revealed the central role of root proteins involved in membrane trafficking in the early response to salinity, such as cell surface receptor-like kinases (RLKs), phosphatidylinositols (PIs), calcium-dependent protein kinases 1 and 5, calcineurin B-like protein-interacting proteins, protein phosphatase 2C (PP2C) inhibitors, and abscisic acid receptors (PYL5/10), indicating activation of S-type anion channel. Furthermore, the proteogenomic analysis revealed 128 unique genome search-specific peptides with high-quality mass spectromety (MS/MS) spectra. We identified 38 novel protein-coding genes, refined the annotation of 17 existing gene models, and suggested several novel stress-responsive proteins, such as RLK5, peroxidase 27, and growth-regulating factor 2. Novel peptides had an ortholog match in the curated protein sequence set of other plant species. In conclusion, this study identifies novel stress-responsive proteins and genes of rice, thus warrant future consideration as candidates for molecular breeding of stress-tolerant crop varieties.

The jojoba genome reveals wide divergence of the sex chromosomes in a dioecious plant

Most flowering plants are hermaphrodites, but around 6% of species are dioecious, having separate male and female plants. Sex chromosomes and some sex-specific genes have been reported in plants, but the genome sequences have not been compared. We now report the genome sequence of male and female jojoba (Simmondsia chinensis) plants, revealing a very large difference in the sex chromosomes. The male genome assembly was 832 Mb and the female 822 Mb. This was explained by the large size differences in the Y chromosome (37.6 Mb) compared with the X chromosome (26.9 Mb). Relative to the X chromosome, the Y chromosome had two large insertions each of more than 5 Mb containing more than 400 genes. Many of the genes in the chromosome-specific regions were novel. These male-specific regions included many flowering-related and stress response genes. Smaller insertions found only in the X chromosome totalled 877 kb. The wide divergence of the sex chromosomes suggests a long period of adaptation to diverging sex-specific roles. Male and female plants may have evolved to accommodate factors such as differing reproductive resource allocation requirements under the stress of the desert environment in which the plants are found. The sex-determining regions accumulate genes beneficial to each sex. This has required the evolution of many more novel sex-specific genes than has been reported for other organisms. This suggest that dioecious plants provide a novel source of genes for manipulation of reproductive performance and environmental adaptation in crops.

Role of proteases in the response of plants to drought

Plants are sessile organisms that, to survive they develop response mechanisms under water deficit conditions. Plant proteases play an essential role in a diversity of biological processes, among them tolerance to drought stress. Proteolysis is a critical regulator of stomatal development. Plant proteases are involved in the crosstalk among phytohormones and adjustment of stomatal aperture. Plant proteases are also related to the increment in reactive oxygen species (ROS) production detected in the plant biochemical response to drought. Plant proteases mitigate this process by degrading damaged, denatured, and aggregated proteins, remobilizing amino acids, and generating molecules involved in signal transductions. Although many roles for proteases have been proposed, molecular bases that regulate these mechanisms remain unknown. In this review, we summarize the current knowledge on the participation of proteases in the signaling pathways of plants in response to water deficit and their relationship with plant stress tolerance.

Fab Advances in Fabaceae for Abiotic Stress Resilience: From 'Omics' to Artificial Intelligence

Legumes are a better source of proteins and are richer in diverse micronutrients over the nutritional profile of widely consumed cereals. However, when exposed to a diverse range of abiotic stresses, their overall productivity and quality are hugely impacted. Our limited understanding of genetic determinants and novel variants associated with the abiotic stress response in food legume crops restricts its amelioration. Therefore, it is imperative to understand different molecular approaches in food legume crops that can be utilized in crop improvement programs to minimize the economic loss. 'Omics'-based molecular breeding provides better opportunities over conventional breeding for diversifying the natural germplasm together with improving yield and quality parameters. Due to molecular advancements, the technique is now equipped with novel 'omics' approaches such as ionomics, epigenomics, fluxomics, RNomics, glycomics, glycoproteomics, phosphoproteomics, lipidomics, regulomics, and secretomics. Pan-omics-which utilizes the molecular bases of the stress response to identify genes (genomics), mRNAs (transcriptomics), proteins (proteomics), and biomolecules (metabolomics) associated with stress regulation-has been widely used for abiotic stress amelioration in food legume crops. Integration of pan-omics with novel omics approaches will fast-track legume breeding programs. Moreover, artificial intelligence (AI)-based algorithms can be utilized for simulating crop yield under changing environments, which can help in predicting the genetic gain beforehand. Application of machine learning (ML) in quantitative trait loci (QTL) mining will further help in determining the genetic determinants of abiotic stress tolerance in pulses.

Investigation of Distinctive Morpho-Physio and Biochemical Alterations in Desi Chickpea at Seedling Stage Under Irrigation, Heat, and Combined Stress

Global climatic instabilities have become the main reason for drastic yield losses in chickpea. This shift in climate could be a great threat in the future for food security in developing countries. Chickpea production is badly hampered by heat stress coupled with drought stress, and these factors can reduce yields by 40-45%. To mitigate yield losses due these abiotic factors, irrigation supplementation could be the best strategy. The present study aimed to (i) investigate the tolerance response of 9 desi chickpea genotypes against heat stress (H), irrigation (I), and a combination of both (I+H) through morphophysiological and biochemical indices at early growth stage, and (ii) assess yield performance across multiple locations of the country. Results revealed that under irrigation treatment, all genotypes perform well, but the genotypes D-09027 and D-09013 showed best performance because, as compared to control, they retained root length, seedling fresh weight, root fresh weight, root dry weight, esterase activity, Malondialdehyde (MDA) content, total chlorophyll, and total carotenoids. Shoot length and total phenolic contents (TPC) increased in both genotypes. Superoxide dismutase (SOD) and peroxidase (POD) increased in D-09027 and retained in D-09013. Catalase activity increased in D-09013 and retained in D-09027. Protease activity, total water potential and osmotic potential decreased in both genotypes and depicted high yield potential with 27 and 30% increase in yield over Bhakhar-2011 (check), respectively. In case of heat stress, maximum tolerance was found in genotypes CH104/06 and D-09013 with no change in shoot and root length, seedling dry weight, shoot fresh and dry weight, root dry weight, relative water content, turgor water potential, catalase (CAT) activity, esterase activity, increased root fresh weight, peroxidase activity (POD), ascorbate peroxidase activity (APX), and lycopene with low accumulation of protease and Malondialdehyde content (MDA). Both genotypes depicted high yield potential with 30 and 43% increase in yield over check across multiple locations of the country. Under the combined treatment, most genotypes showed good performance, while CH104/06 was selected as best performer genotype because significant of its increased root fresh weight, lycopene content, chlorophyll b, total carotenoids, total chlorophyll, retained shoot length, root length, seedling fresh and dry weight, total water potential, osmotic potential, relative water content, peroxidase activity (POD), catalase, esterase, and its ascorbate peroxidase (APX) activity and total soluble proteins (TSP) showed highest yield potential with 43% increase over check. Identified best performing and tolerant genotypes can further be employed for breeding climate-smart chickpea genotypes for sustainable production under changing climate.

Genotype- and tissue-specific physiological and biochemical changes of two chickpea (Cicer arietinum) varieties following a rapid dehydration

In nature, plants may suffer rapid dehydration (RD), which causes significant loss of the annual global chickpea production. Thus, ascertaining more knowledge concerning the RD-tolerance mechanisms in chickpea is crucial for developing high drought-tolerant varieties to assure sustainable chickpea production under sudden water deficit. Here, we focused on genotype-driven variation in leaf relative water content (RWC) and associated differences in RD-responsive physiological and biochemical attributes in roots and leaves of two chickpea varieties, FLIP00-21C and FLIP02-89C, subjected to well-watered and RD conditions. FLIP00-21C showed higher RD-tolerance than FLIP02-89C, evident by its higher leaf RWC during RD. Consistently, FLIP00-21C exhibited lower membrane injury due to lower hydrogen peroxide (H₂ O₂ ) accumulation than FLIP02-89C during RD, indicating reduced RD-induced oxidative damage. Under RD conditions, total phenolics in roots and flavonoids in roots and leaves increased more in FLIP02-89C compared to FLIP00-21C; however, the increased activities of superoxide dismutase and H₂ O₂ -scavenging enzymes were more properly coordinated in FLIP00-21C than in FLIP02-89C, which might contribute to more efficient antioxidant defense in FLIP00-21C than in FLIP02-89C. The higher leaf RWC of FLIP00-21C versus FLIP02-89C under RD might be associated with greater increases in the levels of the osmo-regulators proline and total free amino acids (TFAAs) in FLIP00-21C than in FLIP02-89C. Collectively, the higher RD-tolerance of FLIP00-21C is mainly associated with the maintenance of higher RWC, stronger antioxidant defense, and greater accumulation of proline and TFAAs. These traits could be useful for evaluating the drought-tolerance of chickpea varieties and further marker-assisted breeding approaches for improvement of chickpea productivity.